JP2016020777A - Water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water heater in which drain less likely stays in a heat exchanger, and which can smoothly discharge the drain to the outside.SOLUTION: A fan 6 is for sucking a combustion gas after going through a secondary heat exchanger 4 and exhausting it to the outside of a water heater 1. A drain discharge pipe 10a is connected to the secondary heat exchanger 4 so as to discharge drain generated by latent heat being recovered in the secondary heat exchanger 4 to the outside of the secondary heat exchanger 4. An air passage pipe 10b is connected to an exhaust box 5. A three-way piping joint 10d has a flow passage which joins the drain discharge pipe 10a and the air passage pipe 10b, and also, the flow passage after joining is communicated with the outside of the water heater 1. The three-way piping joint 10d is arranged at a position in which height position C in which a flow passage 10da1 on the drain discharge pipe 10a side and the flow passage 10db1 on the air passage pipe 10b side are joining is lower than a height position B of an air suction port 5aa, and a water head pressure by a height difference between the height position C and the height position B becomes larger than an absolute value of a maximum negative pressure generating in the air suction port 5aa.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hot water supply apparatus, and more particularly to a latent heat recovery type hot water supply apparatus capable of heating hot water by recovering latent heat of combustion gas.

  When replacing an installed hot water storage type hot water supply device with an instantaneous type hot water supply device, there is a site where the installed exhaust pipe cannot be removed from the viewpoint of maintaining the appearance of the building.

  In the field as described above, it is possible to cope with replacement of the hot water supply apparatus by leaving the existing exhaust pipe and inserting the exhaust pipe into the exhaust pipe. However, if the outer diameter of the exhaust pipe is large, the exhaust pipe cannot be installed in the exhaust cylinder, so it is necessary to reduce the diameter of the exhaust pipe. In order to maintain a stable combustion state even when the diameter of the exhaust pipe is reduced, it is necessary to employ an exhaust suction combustion system in the hot water supply apparatus.

  This exhaust suction combustion type hot water supply apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-186617. In the hot water supply apparatus described in this publication, a heat exchanger for recovering sensible heat, a heat exchanger for recovering latent heat, and a fan are disposed downstream of the flow of combustion gas generated in the burner. Arranged in order. That is, in this type of hot water supply apparatus, the fan is disposed downstream of the flow of the combustion gas rather than the heat exchanger for recovering latent heat.

JP-A-60-186617

  In the above-described exhaust suction combustion type hot water supply apparatus, since the fan is arranged downstream of the heat exchanger for recovering latent heat, air (from the outside of the hot water supply apparatus through the discharge pipe for discharging the drain ( Outside air) is taken inside. The direction of air flow in the discharge pipe is opposite to the direction in which the drain is discharged in the discharge pipe. For this reason, there is a problem that the drain is not easily discharged to the outside of the hot water supply apparatus through the discharge pipe, and is liable to stay in the heat exchanger for recovering latent heat.

  Even if a drain seal such as the above drain pipe has a water seal structure that can block the intake of outside air due to the accumulation of drain, the drain pipe will pass through the drain pipe within the period until the drain accumulates and is sealed. Air is taken into the interior from the outside of the water heater. In addition, even if a bypass is provided in the discharge path in order to reduce the flow rate of air flowing into the heat exchanger within the period until it is sealed with water, drain may flow into the bypass from the heat exchanger. is there. There is a problem that the drain that flows into the bypass reflows into the heat exchanger or flows into an undesirable position through the bypass.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hot water supply device in which drain does not easily stay in the heat exchanger and can be smoothly discharged to the outside. is there.

  A hot water supply apparatus of the present invention is a latent heat recovery type hot water supply apparatus capable of heating hot water by recovering the latent heat of combustion gas, and comprises a burner, a heat exchanger, a fan, a drain discharge pipe, and an air passage pipe. And a pipe connection part. The burner is for generating combustion gas. The heat exchanger is for heating hot water flowing inside through heat exchange with combustion gas generated in the burner. The fan sucks the combustion gas after passing through the heat exchanger and discharges it to the outside of the hot water supply apparatus. The drain discharge pipe is connected to a drain discharge port provided in the heat exchanger in order to discharge drain generated by collecting latent heat in the heat exchanger to the outside of the heat exchanger. The air passage pipe is connected to an air suction port provided in the flow path of the combustion gas from the heat exchanger to the fan. The pipe connecting portion has a flow path for joining the drain discharge pipe and the air passage pipe, and connects the flow path after the joining to a discharge path communicating with the outside of the hot water supply apparatus. The height position where the flow path on the drain discharge pipe side and the flow path on the air passage pipe side merge at the pipe connection portion is lower than the height position of the air suction port, and the height position where the flow merges and the air The pipe connection portion is arranged so that the water head pressure due to the height difference from the height position of the suction port is larger than the absolute value of the maximum negative pressure generated at the air suction port.

  According to the hot water supply apparatus of the present invention, since it is an exhaust suction combustion type hot water supply apparatus, air is taken into the hot water supply apparatus from the outside of the hot water supply apparatus through the pipe connection portion. The pipe connecting part joins the drain discharge pipe and the air passage pipe, and connects the flow path after the joining to the discharge path communicating with the outside of the hot water supply apparatus. For this reason, the air which enters the inside of the hot water supply device from the outside of the hot water supply device through the pipe connection portion is divided into both the drain discharge pipe and the air passage pipe from the pipe connection portion. Thereby, compared with the case where air passes only a drain discharge pipe, the flow volume of the air which passes a drain discharge pipe can be reduced. Therefore, it becomes easy to discharge the drain from the drain discharge pipe, and the drain is less likely to stay in the heat exchanger.

  On the other hand, the drain discharged from the drain discharge pipe may stay in the air passage pipe without being discharged outside the hot water supply apparatus from the discharge path side. This is because the air suction port is located closer to the fan than the drain discharge port, so a negative pressure with a larger absolute value than that in the drain discharge tube is generated in the air passage pipe connected to the air suction port. Therefore, the drain discharged from the flow path on the drain discharge pipe side may be drawn into the flow path on the air passage pipe side.

  In the above case, as the drain continues to be discharged from the drain discharge pipe, the height position where the flow path on the drain discharge pipe side and the flow path on the air passage pipe side merge (the height of the merge height) and the height of the air suction port The amount of drain that is drawn into the flow path between the two positions and stays increases. If the drain water level (upper end position) reaches the height of the air intake port, the drain may flow into the combustion gas flow path from the air intake port.

  On the other hand, in the hot water supply apparatus of the present invention, the confluence height position is lower than the height position of the air suction port, and the water head pressure due to the difference in height between the confluence height position and the height position of the air suction port. However, the pipe connection arrangement is arranged so as to be larger than the absolute value of the maximum negative pressure generated at the air suction port. Thereby, the water head pressure of the accumulated drain becomes larger than the absolute value of the maximum negative pressure generated in the air suction port before the drain water level reaches the height position of the air suction port. When the water head pressure of the drain is larger than the absolute value of the maximum negative pressure generated at the air suction port, the drawn drain can easily flow to the discharge path side located below the air passage pipe. For this reason, the drain can be smoothly discharged to the outside.

  In the above hot water supply apparatus, the merging height position is lower than the drain discharge port height position, and the water head pressure due to the height difference between the merging height position and the drain discharge port height is the air suction port. It is preferable that the pipe connecting portion is arranged so as to be larger than the absolute value of the maximum negative pressure generated in the above.

  Since negative pressure is generated at the drain discharge port, the drain that flows out from the heat exchanger to the drain discharge pipe may stay in the drain discharge pipe without being discharged to the discharge path side. In the above case, as the drain continues to be discharged from the heat exchanger, the amount of drain staying in the flow path between the merge height position and the drain discharge port height position increases. If the drain water level (upper end position) reaches the height of the drain outlet, the drain may flow into the heat exchanger from the drain outlet.

  In contrast, the confluence height position is lower than the drain discharge port height position, and the water head pressure due to the difference in height between the confluence height position and the drain discharge port height is the maximum negative pressure generated at the air intake port. By placing the pipe connection at a position where the absolute value of the drain becomes larger, the head pressure of the accumulated drain is the maximum generated at the drain outlet before the drain water level reaches the drain outlet height position. It becomes larger than the absolute value of negative pressure. This is because the absolute value of the maximum negative pressure generated at the air suction port is larger than the absolute value of the maximum negative pressure generated at the drain discharge port because the air suction port is located closer to the fan than the drain discharge port. .

  When the water head pressure of the drain is larger than the absolute value of the maximum negative pressure generated at the drain discharge port, the drain staying in the drain discharge pipe can easily flow to the discharge path side located below the drain discharge pipe. For this reason, the drain can be smoothly discharged to the outside.

  Preferably, the hot water supply apparatus further includes an exhaust box that constitutes at least part of a flow path of the combustion gas between the heat exchanger and the fan, and the air suction port is provided in the exhaust box.

  Even when the air passage pipe is connected to the exhaust box in this way, the air that enters the hot water supply apparatus from the outside of the hot water supply apparatus through the pipe connection section is divided into both the drain discharge pipe and the air passage pipe from the pipe connection section. Can do. This makes it difficult for the drain to stay in the heat exchanger as described above.

  In the above hot water supply apparatus, the pipe connection part is preferably a pipe joint that joins the drain discharge pipe and the air passage pipe.

  Thereby, the drain discharge pipe, the air passage pipe, and the discharge path can be easily connected to each other.

  In the hot water supply apparatus, the fan includes a blade, a drive source, and a rotating shaft that connects the blade and the drive source, and the air passage tube is a flow path of the combustion gas from the heat exchanger to the fan. In this case, it is preferable that the opening is in a region facing the axial direction of the rotation axis of the blade.

  Thereby, an air passage pipe can be opened in a region where the negative pressure is large in the hot water supply apparatus. For this reason, the flow rate of air passing through the air passage tube out of the drain discharge tube and the air passage tube can be increased, and the flow rate of air passing through the drain discharge tube can be reduced accordingly. Therefore, it becomes easier to discharge the drain from the drain discharge pipe.

  As described above, according to the present invention, it is possible to realize a hot water supply apparatus in which drain does not easily stay in the heat exchanger and can be smoothly discharged to the outside.

It is a front view which shows roughly the structure of the hot water supply apparatus in one embodiment of this invention. FIG. 2 is a partial cross-sectional side view schematically showing the configuration of the hot water supply device shown in FIG. 1. It is a schematic perspective view for demonstrating the structure of the secondary heat exchanger of the hot-water supply apparatus shown in FIG. 1, and the drain discharge path | route in a secondary heat exchanger. It is a fragmentary sectional view which expands and shows the fan and secondary heat exchanger for demonstrating the structure of the fan of the hot water supply apparatus shown in FIG. It is a schematic diagram for demonstrating that drain is easy to be discharged | emitted in the hot water supply apparatus in one embodiment of this invention. It is a schematic diagram for demonstrating that drain is hard to be discharged | emitted in the hot water supply apparatus of a comparative example. It is a front view which shows roughly the structure connected to the connection part which an air passage pipe connects an exhaust box and a fan.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of a hot water supply apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  Referring mainly to FIGS. 1 and 2, hot water supply device 1 of the present embodiment is an exhaust suction combustion type latent heat recovery type hot water supply device. The hot water supply device 1 includes a burner 2, a primary heat exchanger 3, a secondary heat exchanger 4, an exhaust box 5, a fan 6, an exhaust pipe 7, a drain trap 8, a housing 9, and a pipe 10. ~ 16.

  The burner 2 is for generating combustion gas by burning fuel gas. A gas supply pipe 11 is connected to the burner 2. The gas supply pipe 11 is for supplying fuel gas to the burner 2. For example, a gas valve (not shown) made of an electromagnetic valve is attached to the gas supply pipe 11.

  Above the burner 2, a spark plug 2a is arranged. The spark plug 2a is for generating a flame in the fuel-air mixture jetted from the burner 2 by generating an ignition spark with a target (not shown) provided in the burner 2. is there. The burner 2 generates heat by burning the fuel gas supplied from the gas supply pipe 11 (this is called a combustion operation).

  Referring mainly to FIG. 2, the primary heat exchanger 3 is a sensible heat recovery type heat exchanger. The primary heat exchanger 3 mainly includes a plurality of plate-like fins 3b, a heat transfer tube 3a that penetrates the plurality of plate-like fins 3b, and a case 3c that accommodates the fins 3b and the heat transfer tubes 3a therein. Have. The primary heat exchanger 3 performs heat exchange with the combustion gas generated in the burner 2, and specifically, in the heat transfer tube 3 a of the primary heat exchanger 3 by the amount of heat generated by the combustion operation of the burner 2. It is for heating the hot water flowing through.

  Referring mainly to FIG. 2 and FIG. 3, the secondary heat exchanger 4 is a latent heat recovery type heat exchanger. The secondary heat exchanger 4 is located downstream of the primary heat exchanger 3 in the flow of the combustion gas, and is connected to the primary heat exchanger 3 in series with each other. Thus, since the hot water supply device 1 of the present embodiment has the latent heat recovery type secondary heat exchanger 4, it is a latent heat recovery type hot water supply device.

  The secondary heat exchanger 4 mainly has a drain discharge port 4a, a heat transfer tube 4b, a side wall 4c, a bottom wall 4d, and an upper wall 4g. The heat transfer tubes 4b are stacked by being spirally wound. The side wall 4c, the bottom wall 4d, and the upper wall 4g are arranged so as to surround the periphery of the heat transfer tube 4b.

  In the secondary heat exchanger 4, hot water flowing in the heat transfer pipe 4 b is preheated (heated) by heat exchange with the combustion gas after heat exchange in the primary heat exchanger 3. In this process, the temperature of the combustion gas is lowered to about 60 ° C., so that moisture contained in the combustion gas is condensed and latent heat can be obtained. Further, the latent heat is recovered by the secondary heat exchanger 4 and the moisture contained in the combustion gas is condensed to generate drain.

  The bottom wall 4 d is for partitioning between the primary heat exchanger 3 and the secondary heat exchanger 4, and is also an upper wall of the primary heat exchanger 3. An opening 4e is provided in the bottom wall 4d, and a space in which the heat transfer tube 3a of the primary heat exchanger 3 is arranged by this opening 4e and a space in which the heat transfer tube 4b of the secondary heat exchanger 4 is arranged. And communicate with each other. As shown by the white arrow in FIG. 2, the combustion gas can flow from the primary heat exchanger 3 to the secondary heat exchanger 4 through the opening 4 e. In this embodiment, for simplicity, the bottom wall 4d of the secondary heat exchanger 4 and the upper wall of the primary heat exchanger 3 are shared, but the primary heat exchanger 3 and the secondary heat exchanger 4 are the same. An exhaust collecting member may be connected between the two.

  An opening 4h is provided in the upper wall 4g, and the space in which the heat transfer tube 4b of the secondary heat exchanger 4 is arranged communicates with the internal space of the exhaust box 5 through the opening 4h. As indicated by white arrows in FIG. 2, the combustion gas can flow from the secondary heat exchanger 4 into the internal space of the exhaust box 5 through the opening 4 h.

  The drain outlet 4a is provided in the side wall 4c or the bottom wall 4d. This drain discharge port 4a is the lowest position in the space surrounded by the side wall 4c, the bottom wall 4d, and the upper wall 4g (the lowest position in the vertical direction when the hot water supply apparatus is installed), and is the lowest position of the heat transfer tube 4b. It opens below the lower end. As a result, the drain generated in the secondary heat exchanger 4 can be guided to the drain outlet 4a through the bottom wall 4d and the side wall 4c as shown by black arrows in FIGS.

  Referring mainly to FIGS. 2 and 4, the exhaust box 5 constitutes a flow path of the combustion gas between the secondary heat exchanger 4 and the fan 6. With this exhaust box 5, it is possible to guide the combustion gas after heat exchange in the secondary heat exchanger 4 to the fan 6. The exhaust box 5 is attached to the secondary heat exchanger 4 and is located downstream of the secondary heat exchanger 4 in the flow of the combustion gas.

  The exhaust box 5 mainly has a box body 5a and a fan connection portion 5b. The internal space of the box body 5a communicates with the internal space where the heat transfer tube 4b of the secondary heat exchanger 4 is disposed through the opening 4h of the secondary heat exchanger 4. An air suction port 5aa is provided at, for example, a side portion of the box body 5a so as to communicate with the internal space of the box body 5a. A fan connecting portion 5b is provided so as to protrude from the upper portion of the box body 5a. The fan connecting portion 5b has, for example, a cylindrical shape, and the internal space 5ba communicates with the internal space of the box body 5a.

  Referring mainly to FIG. 1 and FIG. 2, the fan 6 sucks the combustion gas that has passed through the secondary heat exchanger 4 (heat exchanged in the secondary heat exchanger 4) and sucks the combustion gas of the hot water supply device 1. It is for discharging to the outside and is connected to an exhaust pipe 7 located outside the hot water supply device 1.

  This fan 6 is located downstream of the exhaust box 5 and the secondary heat exchanger 4 in the flow of the combustion gas. That is, in the hot water supply device 1, the burner 2, the primary heat exchanger 3, the secondary heat exchanger 4, the exhaust box 5, and the fan 6 are arranged in order from the upstream side to the downstream side of the flow of combustion gas generated in the burner 2. Are lined up. In this arrangement, since the combustion gas is sucked and exhausted by the fan 6 as described above, the hot water supply apparatus 1 of the present embodiment is an exhaust suction combustion type hot water supply apparatus.

  The fan 6 mainly has blades 6a, a fan case 6b, a drive source 6c, and a rotating shaft 6d. The fan case 6b is attached to the fan connection portion 5b of the exhaust box 5 so that the internal space of the fan case 6b communicates with the internal space of the fan connection portion 5b. As a result, as shown by the white arrows in FIGS. 2 and 4, the combustion gas can be sucked into the fan case 6 b from the box body 5 a of the exhaust box 5 through the fan connection portion 5 b.

  Referring mainly to FIG. 4, blade 6a is arranged inside fan case 6b. The blade 6a is connected to a drive source 6c with a rotating shaft 6d interposed therebetween. As a result, the blade 6a can be rotated about the rotation shaft 6d by receiving a driving force from the driving source 6c. By the rotation of the blade 6a, the combustion gas in the exhaust box 5 can be sucked from the inner peripheral side of the blade 6a and discharged to the outer peripheral side of the blade 6a.

  Referring mainly to FIG. 1, the exhaust pipe 7 is disposed outside the hot water supply device 1 and connected to the outer peripheral side of the fan case 6b. For this reason, the combustion gas discharged to the outer peripheral side by the blade 6 a of the fan 6 can be discharged to the outside of the hot water supply device 1 through the exhaust pipe 7.

  Referring mainly to FIG. 2, the combustion gas generated in the burner 2 by the above is sucked into the fan 6 by the rotation of the blade 6a, so that the primary heat exchanger 3, After passing through the secondary heat exchanger 4 and the exhaust box 5 in this order, the fan 6 can be reached and exhausted to the outside of the hot water supply apparatus 1.

  Referring mainly to FIG. 1, the drain trap 8 is a drain trap capable of sealing the flow path with drain, and is for storing drain generated in the secondary heat exchanger 4. The drain trap 8 mainly has a bent portion 8a and a bent portion 8b. One end of the drain trap 8 communicates with the secondary heat exchanger 4 by a pipe 10 described later, and the other end of the drain trap 8 is It is connected to a drain discharge pipe 15 that communicates with the outside.

  The drain that has flowed into the drain trap 8 from the secondary heat exchanger 4 is stored from below the bent portion 8a. When the water level becomes higher than the upper end of the flow path located at the lower portion of the bent portion 8a, the outside air (air outside the hot water supply apparatus 1) that has entered the bent portion 8b of the drain trap 8 from the drain discharge pipe 15 is discharged into the drain trap. It becomes impossible to flow through the 8 bent portions 8a to the drain discharge pipe 10a side. The water seal structure of the drain trap 8 prevents outside air from passing through the drain trap 8 and entering the hot water supply apparatus 1.

  Referring mainly to FIGS. 1 and 5, the drain trap 8 and the drain discharge port 4a of the secondary heat exchanger 4 are constituted by a drain discharge pipe 10a, a drain trap connecting pipe 10c, and a three-way pipe joint (pipe connecting part) 10d. It is connected. One end of the drain discharge pipe 10a is connected to the drain discharge port 4a of the secondary heat exchanger 4, and the other end is connected to the opening 10da of the three-way pipe joint 10d. Further, one end of the drain trap connecting pipe 10 c is connected to the opening 10 dc of the three-way pipe joint 10 d, and the other end is connected to the drain trap 8.

  Further, one end of an air passage pipe 10b is connected to the air suction port 5aa of the exhaust box 5, and the other end of the air passage pipe 10b is connected to the opening 10db of the three-way pipe joint 10d.

  The three-way pipe joint 10d includes a merging area 10d1 (area shown by hatching in FIG. 5), a flow path 10da1 on the drain discharge pipe 10a side, a flow path 10db1 on the air passage pipe 10db side, and a drain trap connection pipe 10dc side. And a flow path 10dc1. The flow path 10da1 on the drain discharge pipe 10a side is a flow path in the three-way pipe joint 10d between the merging region 10d1 and the opening 10da. The flow path 10db1 on the air passage tube 10b side is a flow path in the three-way pipe joint 10d between the merging region 10d1 and the opening 10db. The flow path 10dc1 on the drain trap connecting pipe 10c side is a flow path in the three-way pipe joint 10d between the merge region 10d1 and the opening 10dc.

  Thus, the three-way pipe joint 10d has a flow path (the flow path 10db1 on the air passage pipe side, the flow path 10da1 on the drain discharge pipe side, and the merge area 10d1) that joins the air passage pipe 10b and the drain discharge pipe 10a. In addition, a flow path (flow path 10dc1 on the drain trap connecting pipe 10c side) that connects the flow path after merging to a discharge path that communicates with the outside of the hot water supply device 1 is provided. In the present embodiment, the discharge path is mainly constituted by the drain trap connecting pipe 10 c, the drain discharge pipe 15 and the drain trap 8. Further, the merge area 10d1 is an area where three flow paths (the flow path 10da1 on the drain discharge pipe 10a side, the flow path 10db1 on the air passage pipe 10b side, and the flow path 10dc1 on the drain trap connection pipe 10c side) merge.

  A drain / branch branched from the drain trap 8 and connected to both the secondary heat exchanger 4 and the exhaust box 5 by the drain discharge pipe 10a, the air passage pipe 10b, the drain trap connection pipe 10c and the three-way pipe joint 10d. A pipe 10 for air is configured.

As shown in FIG. 5, the three-way pipe joint 10d is arranged at a position where the height position C of the merge area 10d1 is lower than the height position B of the air suction port 5aa. Further, the three-way pipe fitting 10d, rather than the absolute value F of the maximum negative pressure head pressure due to the height difference between the height position C and height B (mmH ₂ O) is generated in the air inlet 5aa (mmH ₂ O) It is arranged at a height that will increase.

  Here, the “height position C of the merging region 10d1” means that the height position of the lowest end of the location where the channel 10da1 on the drain discharge pipe 10a side is connected to the merging region 10d1 and the channel 10db1 on the air passage tube 10b side are It means the lower one of the height positions at the lowermost end of the location connected to the merge region 10d1. In the present embodiment, as shown in FIG. 1 and FIG. 5, the shortest distance between the lower end of the flow path 10da1 on the drain discharge pipe 10a side and the upper end of the flow path 10dc1 on the drain trap connection pipe 10c side is small (and The lower end of the flow path 10da1 on the discharge pipe 10a side coincides with the upper end of the flow path 10dc1 on the drain trap connection pipe 10c side). For this reason, in the present embodiment, the height position C is the lower end of the flow path 10da1 on the drain discharge pipe 10a side. The “height position B of the air suction port 5aa” is the height position of the lower end of the air suction port 5aa.

  The “upper end” and “lower end” of each part in the pipe 10 are the “upper end” where the height position is closer to the height position of the fan 6, and the end portion farther from the height position of the fan 6 is “ "Bottom". In the installed state of the hot water supply device 1, the lowermost position in the vertical direction corresponds to the “lower end”, and the uppermost position corresponds to the “upper end”.

  The drain discharge pipe 10a preferably has a horizontal or downward slope from the drain discharge port 4a to the three-way pipe joint 10d. Thereby, it becomes possible to flow the drain smoothly from the secondary heat exchanger 4 to the drain trap 8 side.

  Referring mainly to FIGS. 1 and 2, the water supply pipe 12 is connected to one end of the heat transfer pipe 4 b of the secondary heat exchanger 4, and the tapping pipe 13 is one of the heat transfer pipes 3 a of the primary heat exchanger 3. Connected to the end. The other end of the heat transfer tube 3 a of the primary heat exchanger 3 and the other end of the heat transfer tube 4 b of the secondary heat exchanger 4 are connected to each other by a connection pipe 14. Each of the gas supply pipe 11, the water supply pipe 12, and the hot water supply pipe 13 communicates with the outside at the upper part of the hot water supply apparatus 1, for example. Further, the burner 2, the primary heat exchanger 3, the secondary heat exchanger 4, the exhaust box 5, the fan 6, the drain trap 8 and the like are arranged in the housing 9.

  Next, the effect of the hot water supply apparatus of this Embodiment is demonstrated compared with the comparative example shown in FIG.

  In the hot water supply apparatus of the comparative example shown in FIG. 6, the drain discharge pipe 10 that connects the drain trap 8 and the secondary heat exchanger 4 to each other is not branched. In addition, in the structure of the comparative example other than this, since the structure of the hot water supply apparatus of this Embodiment mentioned above is substantially the same, the description is not repeated.

  The hot water supply apparatus of this comparative example is an exhaust suction combustion type hot water supply apparatus, similar to the hot water supply apparatus 1 of the present embodiment shown in FIG. In this type of hot water supply apparatus, as shown in FIG. 1, the fan 6 is arranged downstream of the flow of the combustion gas rather than the secondary heat exchanger 4 for recovering latent heat. For this reason, in the period until the drain trap 8 is sealed with water, the hot water supply device is passed through the drain discharge path (drain discharge pipe 15, drain trap 8, drain trap connecting pipe 10c, three-way pipe joint 10d and drain discharge pipe 10a). Outside air is taken into the secondary heat exchanger 4.

  For this reason, as shown in FIG. 6, the air flowing direction (white arrow in the figure) in the drain discharge pipe 10 is opposite to the drain discharge direction (black arrow in the figure). Therefore, the drain is less likely to be discharged to the drain trap 8 side through the drain discharge pipe 10 and is likely to stay in the secondary heat exchanger 4.

  If the drain in the secondary heat exchanger 4 is stored without being discharged, the drain may overflow to the primary heat exchanger 3 side through the opening 4e shown in FIG. In this case, the overflowed drain may corrode the heat transfer tube 3a made of, for example, copper of the primary heat exchanger 3, corrodes the burner 2 made of, for example, stainless steel, or the flame of the burner 2 disappears.

  On the other hand, according to the hot water supply apparatus 1 of the present embodiment, the other end of the pipe 10 whose one end is connected to the drain trap 8 branches as shown in FIG. It is connected to both boxes 5. For this reason, the air that enters the hot water supply device 1 from the outside of the hot water supply device 1 is divided into air that enters the secondary heat exchanger 4 side and air that enters the exhaust box 5 side. Thereby, the flow volume of the air (air passing through the drain discharge pipe 10a) entering the secondary heat exchanger 4 side can be reduced more than the flow volume in the drain trap connection pipe 10c. Therefore, it becomes easy to discharge the drain to the drain trap 8 side through the drain discharge pipe 10a, and the drain is less likely to stay in the secondary heat exchanger 4.

  As shown in FIG. 1, an air passage pipe 10 b is connected to the exhaust box 5. The exhaust box 5 is located closer to the fan 6 than the secondary heat exchanger 4. For this reason, the negative pressure is higher in the internal space of the exhaust box 5 than in the internal space of the secondary heat exchanger 4. As a result, the amount of air entering the secondary heat exchanger 4 side can be made smaller than the amount of air entering the exhaust box 5 side, so that it becomes easier to discharge the drain from the drain discharge pipe 10a. It becomes difficult to stay in the secondary heat exchanger 4.

  By the way, since the air passage pipe 10b is connected to the exhaust box 5, a negative pressure is generated in the merging region 10d1 and the flow path 10db1 on the air passage pipe 10b side. This negative pressure serves as a force for drawing the drain from the merge region to the air suction port 5aa.

  For this reason, even if the drain generated in the secondary heat exchanger 4 is discharged from the drain discharge pipe 10a and reaches the merge area 10d1, the drain flows toward the drain trap connection pipe 10c due to the negative pressure as described above. Cannot stay in the merging region 10d1, the flow path 10db1 on the air passage pipe 10b side, and in the air passage pipe 10b, that is, in the flow path between the height position B and the height position C of the pipe 10. There is a case.

  In the above case, as the drain continues to be discharged from the drain discharge pipe 10a, the amount of drain staying in the flow path between the height position B and the height position C increases. If the water level (upper end position) of the staying drain reaches the height position B of the air suction port 5aa, the drain may flow into the exhaust box 5 from the air suction port 5aa. When a large amount of drain is introduced into the exhaust box 5, there arises a problem that the blowing capacity of the fan 6 is lowered or the fan 6 is corroded.

On the other hand, according to the hot water supply apparatus 1 of the present embodiment, as shown in FIG. 5, the three-way pipe joint 10d is arranged at a position where the height position C is lower than the height position B of the air suction port 5aa. The And the three-way pipe fitting 10d is head pressure due to the height difference between the height position C and height B (mmH ₂ O) is, than the absolute value F of the maximum negative pressure generated in the air inlet 5aa (mmH ₂ O) Is also arranged to be larger.

  As a result, regarding the drain remaining in the flow path between the height position B and the height position C of the pipe 10, the water head pressure of the drain itself before the water level reaches the height position B of the air suction port 5aa. Becomes larger than the absolute value F. When the water head pressure of the drain itself is larger than the absolute value F, the drain can easily flow into the flow path on the drain trap connecting pipe 10c side. For this reason, according to the hot water supply device 1 according to the present embodiment, the drain can be easily discharged to the drain trap 8 side while suppressing the drain from flowing into the exhaust box 5 from the air suction port 5aa. Therefore, the drain can be smoothly discharged to the outside.

  In particular, after the water seal structure of the drain trap 8 is sealed, the height position B and the height position C in the pipe 10 shown in FIG. Since there is no air flow (indicated by white arrows in the figure) from the lower side in the figure to the upper side in the figure with respect to the flow path between the drains, drainage is further facilitated.

  Further, in the hot water supply apparatus 1 of the present embodiment, the height position C is lower than the height position A of the drain discharge port 4a, and the water head pressure due to the height difference between the height position C and the height position A is air. It is preferable to be disposed at a position where the absolute value F of the maximum negative pressure generated at the suction port 5aa is larger. Here, “the height position A of the drain discharge port 4a” is the height position of the lower end of the drain discharge port 4a. This is due to the following reason.

  In the hot water supply apparatus 1 before the drain trap 8 is sealed with water, the drain discharged from the drain discharge port 4a to the drain discharge pipe 10a does not flow to the drain trap connection pipe 10c side, but the flow path 10da1 on the drain discharge pipe 10a side. Or the drain discharge pipe 10a, that is, the pipe 10 may stay in the flow path between the height position A and the height position C. This is because a negative pressure is also generated in the drain discharge pipe 10a. This negative pressure serves as a force for causing the drain of the flow path between the height position A and the height position C to flow toward the drain discharge port 4a.

  In the above case, as the drain continues to flow from the drain discharge port 4a, the amount of drain staying in the flow path between the height position A and the height position C increases. If the water level (upper end position) of the staying drain reaches the height position A of the drain discharge port 4a, the drain may flow into the secondary heat exchanger 4 from the drain discharge port 4a.

  On the other hand, the height position C is lower than the height position A, and the water head pressure due to the height difference between the height position C and the height position A is greater than the absolute value F of the maximum negative pressure generated at the air suction port 5aa. When the three-way pipe joint 10d is arranged at a position where the drain becomes higher, the water head pressure of the drain staying in the drain discharge pipe 10a before the water level of the drain reaches the height position A is changed to the drain outlet 4a. It becomes larger than the absolute value of the maximum negative pressure generated in This is because the absolute value of the maximum negative pressure generated at the drain discharge port 4a is greater than the absolute value F of the maximum negative pressure generated at the air suction port 5aa when the secondary heat exchanger 4 is positioned upstream of the exhaust box 5. This is because also becomes smaller.

  As a result, regarding the drain accumulated in the flow path between the height position A and the height position C of the pipe 10, before the water level reaches the height position A of the drain discharge port 4 a, Becomes larger than the absolute value of the negative pressure generated in the drain discharge pipe 10a. When the water head pressure of the drain itself is larger than the negative pressure generated in the drain discharge pipe 10a, the drain can easily flow into the flow path on the drain trap connecting pipe 10c side. Therefore, it is possible to prevent the drain from flowing back into the secondary heat exchange 4, so that the drain can be smoothly discharged to the outside.

  Even in the above case, after the water-sealed structure is sealed, the height position A and the height position C in the pipe 10 shown in FIG. Since there is no flow of air from the lower side in the figure to the upper side in the figure with respect to the flow path between them, drainage is further facilitated.

Usually, the fan discharge pressure is _{60mmH 2 O~100mmH 2 O (588.4Pa~980.665Pa)} . Therefore, the absolute value F of the maximum negative pressure generated in the air inlet 5aa also made 60mmH ₂ O~100mmH ₂ O or smaller. Therefore, the height difference between the height position B and the height position C is preferably 60 mmH ₂ O or more, and the height difference between the height position A and the height position C is also preferably 60 mmH ₂ O or more. . In addition, assuming a case where an abnormality in the exhaust path occurs, it is more preferable that the height difference is 100 mmH ₂ O or more.

  In the configuration shown in FIG. 1, the configuration in which the air passage pipe 10 b is connected to the box body 5 a of the exhaust box 5 is described. However, the air passage pipe 10 b is a combustion gas from the secondary heat exchanger 4 to the fan 6. It is only necessary to be connected to the flow path. Here, “the path of the flow of combustion gas from the secondary heat exchanger 4 to the fan 6” means a space in which the combustion gas flows in the secondary heat exchanger 4 and the exhaust box 5 in FIG. In addition, when there is a constituent member other than the exhaust box 5 before reaching the fan 6 from the secondary heat exchanger 4, it also includes a space in which the combustion gas in the constituent member flows.

  For example, as shown in FIG. 7, the air passage pipe 10 b may be connected to the fan connection portion 5 b instead of the box body 5 a of the exhaust box 5. By connecting the air passage pipe 10b to the fan connecting portion 5b of the exhaust box 5 in this way, it can be connected to the exhaust box 5 at a position closer to the fan 6 than when connecting to the box body 5a.

  Thereby, the air passage pipe 10b can be opened in a region where the negative pressure is larger than when connecting to the box body 5a. For this reason, in the period until the drain trap 8 is sealed with water, the flow rate of air passing through the air passage tube 10b out of the drain discharge tube 10a and the air passage tube 10b can be increased, and the flow rate of air passing through the drain discharge tube 10a. Can be further reduced. Therefore, it becomes easier to discharge the drain from the drain discharge pipe 10a.

  Referring to FIG. 4, the air passage tube 10 b is in the direction of the axis SS of the rotary shaft 6 d with respect to the blade 6 a in the flow path of the combustion gas from the secondary heat exchanger 4 to the fan 6. It is preferable to open in the area | region R (area | region which put the hatching in the figure) which opposes. Specifically, a region R (a hatched area in the drawing) is a combination of the internal space 5ba of the fan connecting portion 5b and a region obtained by extending the internal space 5ba in the direction of the axis SS of the rotating shaft 6d. It is preferable that the air passage pipe 10b is opened in the inside.

  Since this region R is a region facing the blade 6a of the fan 6 that sucks in combustion gas, it is a region where the negative pressure increases. For this reason, by opening the air passage pipe 10b in this region R, the flow rate of the air taken into the hot water supply device 1 through the air passage pipe 10b can be increased, and the air passing through the drain discharge pipe 10a accordingly. The flow rate can be further reduced. Therefore, it becomes easier to drain the drain from the drain trap connecting pipe 10c within a period until the drain trap 8 is sealed with water.

  For example, as shown in FIG. 7, by connecting the air passage pipe 10b to the fan connecting portion 5b of the exhaust box 5, the air passage pipe 10b can be opened to the region R where the negative pressure increases.

  Further, in the present embodiment, the exhaust suction combustion type hot water supply apparatus 1 is used as described above, and therefore, even when the diameter of the exhaust pipe 7 is reduced, the burner 2 is used for the so-called exhaust push type hot water supply apparatus. Combustion operation can be stabilized. This will be described below.

  In a so-called exhaust pushing hot water supply apparatus, a fan, a burner, a primary heat exchanger, and a secondary heat exchanger are arranged in this order from the upstream side to the downstream side of the flow of combustion gas. That is, the combustion gas generated in the burner flows into the exhaust pipe outside the hot water supply device through the primary heat exchanger and the secondary heat exchanger by the fan.

  The combustion gas pushed out of the fan is subjected to flow resistance by the primary heat exchanger and the secondary heat exchanger before reaching the exhaust pipe, so the blowing pressure of the combustion gas immediately before the exhaust pipe is equal to this flow resistance. Lower. For this reason, in order to push combustion gas into the exhaust pipe having a small diameter, it is necessary to increase the blowing pressure by the fan. However, if the fan blowing pressure is increased, the internal pressure in the burner case increases. For this reason, when the supply pressure of the fuel gas supplied to the burner is low, the combustion operation becomes unstable.

  On the other hand, according to the exhaust suction combustion system of the present embodiment, the burner 2, the primary heat exchanger 3, the secondary heat exchanger 4 and the fan 6 are arranged from the upstream side to the downstream side of the flow of the combustion gas. They are arranged in this order. In this method, since the negative pressure is upstream of the fan 6, even if the diameter of the exhaust pipe 7 is reduced, the internal pressure in the burner case can be kept low, so that the supply pressure of the fuel gas supplied to the burner 2 can be maintained. Even if it is low, the combustion operation can be stabilized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Hot-water supply apparatus, 2 burner, 2a Spark plug, 3 Primary heat exchanger, 3a, 4b Heat transfer tube, 3b Fin, 3c Case, 4 Secondary heat exchanger, 4a Drain discharge port, 4c Side wall, 4d Bottom wall, 4e, 4h opening, 4g upper wall, 5 exhaust box, 5a box body, 5aa air inlet, 5b fan connection, 5ba internal space, 6 fan, 6a blade, 6b fan case, 6c drive source, 6d rotating shaft, 7 exhaust Pipe, 8 Drain trap, 8a, 8b Bent part, 9 Housing, 10 Pipe, 10a Drain discharge pipe, 10b Air passage pipe, 10c Drain trap connection pipe, 10d Three-way pipe joint, 10da, 10db, 10dc opening, 10d1 Merge area 10 da 1, 10 db 1, 10 dc 1 flow path, 11 gas supply pipe, 12 water supply pipe, 13 tap water pipe, 1 4 Connection piping, 15 Drain discharge piping.

Claims (5)

A latent heat recovery type hot water supply device capable of heating hot water by recovering the latent heat of combustion gas,
A burner for generating the combustion gas;
A heat exchanger that heats hot water flowing inside by heat exchange with the combustion gas generated in the burner;
A fan that sucks the combustion gas after passing through the heat exchanger and discharges it to the outside of the hot water supply device;
A drain discharge pipe connected to a drain discharge port provided in the heat exchanger;
An air passage pipe connected to an air inlet provided in a flow path of the combustion gas from the heat exchanger to the fan;
A pipe connection part having a flow path for joining the drain discharge pipe and the air passage pipe, and connecting the flow path after the merge to a discharge path communicating with the outside of the hot water supply device;
The height position at which the flow path on the drain discharge pipe side and the flow path on the air passage pipe side merge in the pipe connection portion is lower than the height position of the air suction port and merges. The hot water supply in which the pipe connection portion is arranged so that the water head pressure due to the height difference between the height position and the height position of the air suction port is larger than the absolute value of the maximum negative pressure generated at the air suction port. apparatus.   The merged height position is lower than the drain discharge port height position, and water head pressure is generated at the air suction port due to the height difference between the merged height position and the drain discharge port. The hot water supply device according to claim 1, wherein the pipe connection portion is disposed so as to be larger than an absolute value of the maximum negative pressure. An exhaust box further comprising at least part of the path of the flow of the combustion gas between the heat exchanger and the fan;
The hot water supply apparatus according to claim 1 or 2, wherein the air suction port is provided in the exhaust box.   The hot water supply apparatus according to any one of claims 1 to 3, wherein the pipe connection portion is a pipe joint that joins the drain discharge pipe and the air passage pipe. The fan includes a blade, a drive source, and a rotating shaft that connects the blade and the drive source,
The air passage pipe opens in a region facing the axial direction of the rotating shaft of the blade in the path of the flow of the combustion gas from the heat exchanger to the fan. The hot water supply device according to any one of claims 1 to 4.

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